Iron GT-40 Head question
- Thread starter 95CobraMike
- Start date
18mustangs
New Member
95CobraMike said:
That depends where the GT40 heads are from. Cobra GT40 heads have 61cc chambers (I can verify this fact later but don't have my resources at hand) and the Explorer GT40 heads have larger combustion chambers.
Tim
legalize420
Active Member
The Official Ford Mustang 5.0: Technical Reference & Performance Handbook, 1979-1993 lists the combustion chambers as between 63 and 65.5cc on the '93-'95 Cobra heads as well as the Motorsports version which varied only slightly from the production head.
Explorer heads are at approximately 60-61cc.
Explorer heads are at approximately 60-61cc.
18mustangs
New Member
legalize420gt95 said:
That seems like it's talking about Explorere GT40 heads as they need to be milled to give the stock mustang compressions ratio. (I'm guessing here as my Ford Technical CD is still in transit from my move) but GT40s on cobras had 61cc and E7TE had CCs ranging from 61-63 cc each (mass produced GT heads had looser tolerances that Cobra GT40 heads.)
Tim
So if i were to go with a set of heads with 64cc combustion chambers i would have around stock cobra comp. ratio?
the gt-40's on there now have been milled 2 times and i think my comp ratio is too high
the gt-40's on there now have been milled 2 times and i think my comp ratio is too high
95CobraMike said:
Not totally sure here Mike
but
It has always been my understanding that when talking about oem iron heads
you can't mill them all that much before you start to have alignment issues.
Even if you go to that maximun point or just before you have those probs ...
the amount of gain in compression is not all that much.
I don't think you can even gain 1/2 a point
Grady
blksn955.o
Founding Member
Mine are milled .065 and I had to get the lower intake milled to fit correct. I belive the max without milling is like .050-.055 or something like that. I had the intake milled like .025 so it would still be usable and in speck if ever sold (well could be used if someone had a very mild mill on there heads).
I though I saw a thing about the cobra heads (93-95) that the gt40 heads on them were milled from the factory a hair...this could explaine the diff. in "off the shelf" numbers and what others are putting up.
I though I saw a thing about the cobra heads (93-95) that the gt40 heads on them were milled from the factory a hair...this could explaine the diff. in "off the shelf" numbers and what others are putting up.
